vboot2: Add GUIDs for VB2_SIG_NONE signature types
vboot2: Add GUIDs for VB2_SIG_NONE signature types

Signatures with VB2_SIG_NONE are unsigned hashes.  To make it easier
to locate these signatures in the keyblock's list of signatures,
define GUIDs for them.

BUG=chromium:423882
BRANCH=none
TEST=VBOOT2=1 make runtests

Change-Id: I5bf9424107d7703b1a191b1bdf02954192ffc583
Signed-off-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/226813
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>

coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,acorn-marvell/vboot_reference,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,acorn-marvell/vboot_reference,coreboot/vboot,coreboot/vboot